Stoker



May 5, 1942. J. 5. BEQNNETT STOKER Filed Sept. 3, 1936 4 Sheets-Sheet 1 y 5, 1942- J. s. BENNETT 2,282,157

STOKER Filed Sept. 3, 1936 4 Sheets-Sheet 3 mmWWMMmr/W A? M MM A WEPZEEEW May 5,

J. S. BENNETT STOKER I Filed Sept. 3, 1936' 4 Sheets-Sheet 4 Patented May 5, 1942 STOKER Joseph S. Bennett, Merion, Pa., assignor to American Engineering Company, Philadelphia, Pa., a corporation of Pennsylvania Application September 3, 1936, Serial No. 99,234

10 Claims.

This invention relates to stokers, and more particularly to stokers of the inclined grate, multiple retort underfeed type.

One object of the present invention is to provide a generally improved stoker which is economical to manufacture, and which insures the highest efiiciencies throughout the operating range thereof.

Another object is to provide a novel overfeed section in stokers of the stated character which feeds the consumed, as well as the partially consumed fuel and clinker toward an ash pocket.

A further object is to provide a novel grate section, particularly adapted for use with fluid cooled stokers of the underfeed type, the grate section being so disposed as to effectively feed fuel and residue to an ash pocket as well as break up any clinkers forming at the top of the fuel bed.

Other and further objects will become apparent as the description of the invention progresses.

Of the drawings:

Fig. 1 is a longitudinal view taken through one of the stoker retorts, showing the preferred embodiment under the present invention.

Fig. 2 is a plan view partly in section, taken substantially along line 2-2 of Fig, 1.

Fig. 3 is a side elevational view of one of the grate bars of the overfeed section of the stoker shown in Fig. 1.

Fig. 4 is a plan view of the grate bar shown in Fig. 3.

Fig. 5 is an end view taken substantially along line 5-5 of Fig. 3.

Figs. 6, 7 and 8 are side, top and end views respectively, of another form of grate bar for the stoker shown in Figs. 1 and 2.

Fig. 9 is a side elevational view of the overfeed section of a stoker showing grate bars of an alternative construction.

Fig. 10 is a fragmentary plan view of the construction shown in Fig. 9.

Fig. 11 is a detail view of the mechanism for adjusting the lower ends of grate bars shown Figs. 17 and 18 are side and end views respectively of the grate bars disposed between the tubes.

Fig. 19 is a side elevational view partly in section of the overfeed section of a stoker, showing a still further type of construction, and

Fig. 20 is a plan view of the construction shown in Fig. 17 with certain parts broken away to show the construction of the operating mechanism therefor.

Referring to the drawings, the numeral I designates generally a stoker of the inclined grate type, having an upper underfeed section 2, and a lower overfeed section 3.

The underfeed section of the stoker consists of a series of alternately disposed retorts 4 and tuyre rows 5. Fuel is supplied to the stoker from hoppers 6, disposed exteriorly of front wall I, and mounted upon the cylinders 8 of the ram boxes 9. The fuel from hoppers 6 gravitating into one end of cylinders 8 is fed to the retorts 4 by rams l0. Fuel is underfed along the retorts 4, and tuyre rows 5 to dead plates I2, and thence to overfeed section 3 by a series of pushers II. Section 3 then overfeeds the fuel and residue to an ash pocket l9 disposed at the lower rearwardly disposed end of the stoker. The rams I0 are driven by any suitable power mechanism IS. The pushers II are also driven by the power mechanism I3 through any suitable link and lever mechanism indicated generally at I4. Inasmuch as the specific construction of the operating mechanism for the fuel feeding elements forms no part of the present invention a detailed description thereof will not be given herein. For a complete description of such a mechanism reference may be had to United States Patent No. 2,005,005.

As shown in Figs. 1 and 2, each tuyre row has mounted thereon a pair of fluid conducting tubes I5. These tubes extend beyond the lower end of the tuyre rows, as shown at I6, and form a portion of the overfeed section 3, and are then bent downwardly, as shown at IT, to form a portion of the front wall I8 of ash pocket I9, and terminate at their lower ends in a header 2!] supported upon a transverse beam 2|. Tubes l5 also extend upwardly from tuyre rows 5, as shown at 22, and terminate at their upper ends in a boiler (not shown). The portion 22 of tubes I5 make intimate contact with the inner surface of wall 1, and thus constitute a cooling medium for said wall. Mounted beneath and in intimate contact with each dead plate I2 is a pair of tubes 23. These tubes terminate at the forward ends thereof in a header 24 disposed transversely of the stoker, and mounted upon any suitable supporting beam 25. The rearwardly disposed portions of the tubes 23 are bent downwardly in substantial parallel relation with section It of tubes I5, and also form a portion of the overfeed section 3. These tubes are then bent downwardly in substantial parallel relation with section I! of tubes i5, and also terminate in header 23. Headers 29 and 24 are connected to the boiler by any suitable downtake and uptake connections respectively, in a well known manner. Disposed between tubes i and 23, and between the terminal tubes l5, and the furnace side walls 25 and 21 are a series of movable grate bars 28. Also disposed between each pair of tubes 23 is a slightly wider grate bar 29. As shown in Fig. 2, the overfeed section 3 of the stoker is divided into units 3*, 3 and 3. The end units 3 and 3 consist of the same number of grate bars, there being one grate bar 29 disposed centrally of the unit, and two grate bars 28 disposed on either side thereof. The central unit 3 on the other hand, comprises a central grate bar 29 and one grate bar 28 disposed on either side thereof. It is obvious, however, that the number of grate bars 28 and 29 contained in the units may be varied without departing from the present invention. The grate bars of each of the units 3 3 and 3 are rigidly connected near the forward ends thereof for simultaneous movement by rods 39, 3| and 32 respectively. Rods 30, 3| and 32 are operatively connected to reciprocable rods 33, 34 and 35 respectively, which extend through suitable bearings 33 and 31 disposed forwardly of overfeed section 3 and mounted in any suitable manner upon a transverse beam 38. The other ends of said rods are connected to the link and lever mechanism 14 by a second link and lever mechanism 39. The extents of movement of units 3 3 and 3, as well as that of the associated rams and pushers, may be varied by varying the number of washers 299 on the operating mechanism, as shown in Fig. 1. The lower edges 49 and 4| of grate bars 28 and 29 respectively,

are provided with laterally extending bearing flanges 42 and 43. These flanges in assembly rest upon anti-friction rollers 44 mounted for movement "in bearing blocks 45 supported upon atransverse beam 46. Thus, upon operation of the power mechanism I 3 reciprocatory movement will be imparted to the rains l9, pushers H, and units 3 3 ,and 3 of the overfeed section 3. Draft air is supplied to the stoker from'a plenum chamber 4'1,'which in turn is supplied with air ,by any suitable fan mechanism (not shown), through a connecting passage 48. Air is supplied to the overfeed section 3 from a second chamber '49 disposed therebeneath and connected to chamber 41 by a communicating passage '59. Passage 5!! has provided therein a movable damper 5|, whereby the flow of air from chamber 41 to overfeed section 3 may be controlled. Any siftings passing between the grate blocks 28 and 29 collect at the bottom of chamber 49 from which they may be removed from time to time by simply opening a closure member 52 provided at the bottom thereof.

Referring to Figs. 6 to 8, it will be observed that each of the grate bars 28 is of substantially rectangular form, and comprises a relatively thin body portion 53 having an inclined serrated upper edge 54 and an inclined lower edge 56, which terminates at the lower end thereof in the horizontally disposed lower edge 49. In-

clined edge 55 has provided intermediate the ends thereof an apertured bossed portion 51 for receiving rods 33, 3! or 32, as the case may be. The upper end of body portion 53 is provided with a pair of laterally extending projections 59 which, in assembly, rest upon bearing surfaces 69 provided on a bracket 61, secured to and extending rearwardly of the upper front wall 62 of chamber 49.

Referring to Figs. 3 to 5, each grate bar 29 comprises a pair of substantially flat side plates 53 and 64 arranged in spaced relation and connected at the upper inclined edges thereof by a series of offset substantially parallel members 65 arranged in stepped relation. A series of apertures 35 are provided along the upper edge of grate bars 29, through which draft air may pass. The inclined lower edges 61 of the side plates 33 and 64 have each provided intermediate the ends thereof an apertured boss 68 through whichrods 39, 3! or 32, as the case may be, extend. Also extending laterally from each of the side plates 63 and 54 is a relatively flat projection 59. which in assembly rests upon the flat bearing surfaces 39 of brackets 5!.

Figs. 9 to 11 show an alternative construction wherein the lower ends of the tubes 19 provided over each of the tuyere rows '1! of the stoker 12 also form a portion of the overfeed section 13. Disposed between tubes 19 are a series of grate bars 74. The lower edge of each grate bar '14 rests upon a roller 15 rotatably mounted at the free end of an arm H secured to a shaft 18. Shaft 18 extends through the side wall 19 of the furnace and is journalled in a bearing 39 provided in a bracket 99, secured to said side wall. The outer end of shaft 18 has secured thereto a gear 31 which meshes with a second gear 82 mounted on a shaft 63 supported in a secondbearing 85 of bracket 99. A hand crank 86 is secured to one end of shaft 83. Also secured to shaft i8 is a ratchet wheel 31 which is held against movement in one direction by a pawl 83, pivotally supported on bracket 99. Thus upon rotation of gears 82 and SI by crank 8 6, arm i? will be swung about its pivot, to raise or lower supporting rollers '56 to adjust the lower ends of grate bars 14. Pawl 88 engaging ratchet wheel 31 retains the parts in adjusted position. Each of the grate bars 14 is provided with an enlarged aperture 9i near the upper end thereof, in which operates a cam 92 eccentrically mounted on a shaft 92'. Shaft 92 is operated by an electric motor 93 through chain and sprocket mechanism 94 and reduction gearing 95. Thus, upon operation of motor 93, cams 92 are actuated in an orbital path thereby imparting a reciprocatory, as well as a rocking movement to the grate bars '14. In the event it is desired to increase the effectiveness of the overfeed section, the lower ends of grate bars 14 are elevated, as shown in broken lines in Fig. 9, to bring the upper serrated edges thereof a greater distance above the tubes 19. In order to prevent the passage of siftings past the upper ends of the grate bars 14, a series of plates 93 are provided. These plates are pivoted at 91, and the lower rearwardly disposed ends 98 thereof engage the upper edges of the grate bars'l i and thus form a seal between the points of contact thereof. These plates are held in contact with the grate bars i i by any suitable means, such as weights 39.

Figs. 12 to 18 inclusive show a further embodiment of the present invention, wherein the overfeed section I of the stoker I 0| comprises a series of relatively wide overlapping grate blocks I02 in line with the retorts I03, and a series of relatively narrow grate blocks I04 disposed between the pairs of tubes I extending rearwardly from the tuyre rows I06. Supported on transverse beams I01 and I08, in any suitable manner, are a series of inclined supporting members I09 and H0. As shown in Fig. 13, a supporting member I09 extends rearwardly of and in substantial alignment with the end row of tuyres, while a supporting member I I0 extends rearwardly and in substantial alignment with each of the intermediate tuyre rows.

Supporting member I09 consists of a relatively flat plate III having three pairs of horizontally disposed flanges I I2 arranged in stepped relation over the length thereof. The flanges I I2 of each pair are spaced slightly from each other forming a horizontally disposed groove I I3.

Supporting members IIO each comprises a pair of side plates H4 and H5 having three horizontally disposed and relatively flat grate supporting members II6 integral therewith and arranged in offset relation over the length thereof. Extending laterally of side plates H4 and H5, and in substantial alignment with each of the members I I6 are a pair of projections H1 and I I 8. Also extending upwardly from each member H6 and in alignment with plates I I4 and H5 are a pair of vertically extending T-shaped projections I I9 and I20. The outer flanges of projections H9 and I20 are substantially parallel with projections H1 and H8 respectively, and form therewith pairs of open ended grooves I 2| and I22. The inner flanges of projections H9 and I20 form with the upper surfaces of members I I6 guide slots I23 of substantially inverted T-shaped form.

Referring more particularly to Figs. 14 to 16, it will be seen that each of the grate bars I02 comprises a pair of substantially triangular side plates I24 and I25 connected at the upper ends thereof by a relatively flat bearing portion I26 and an inclined fuel feeding portion I21. The lower, rearwardly disposed ends of side plates I24 and I25 are offset, as shown at I28, forming a bearing portion which rests upon the bearing portion I26 of the next lower grate block of the series. Side plates I24 and I 25 are also provided with longitudinally extending projections I29 and I 30, which in assembly operate in grooves H3 or H8, and H1 respectively, of supporting members I09 and H0, as shown in Fig, 13. Depending from the lower surface of inclined member I21 is a web I3I, which terminates at the lower end thereof in a pair of spaced bosses I32 and I33 extending inwardly of side plates I24 and I25. Side plate I24 and boss I32 are provided with a transverse aperture I34 in alignment with a transverse aperture I35 extending through boss I33 and wall I25. Apertures I34 and I35 in assembly receive a rod I 36 to which is pivotally connected one end of a link I31. The other end of link I31 is pivotally connected to the upper ends of a pair of levers I38 journaled on a rod I39 mounted in plates H4 and H5 of adjacent supporting members H0, or in the lower end I40 of supporting member I 09 and plate II4 of a supporting member IIO when disposed near the side walls of the furnace. The levers I38 for the pp te block I02 of each series are pivotally connected to the free end of a link IN, the other end of which being pivotally connected to a p ng member I42 secured to a reciprocatory rod I43 mounted in bearings I44 and I45. Bearings I44 and I45 are mounted on beams I46 and I41 respectively, as shown in Fig. 12. The lower ends of the levers I38 for the second and third grate bars I02 of the series are respectively connected to the free ends of links I48 and I49, the other ends of which being also pivotally connected to the coupling member I42.

Grate bars I04 are also of substantially triangular construction and each comprises a relatively thin web portion I50, which extends vertically between a pair of tubes I05, and a lower flanged portion I5I which engages in the slot I 23 provided in the supporting members IIO. Each grate bar I04 is rigidly secured to and held in spaced relation with the grate bar I02 disposed to the left thereof by bolts I52, or by any other suitable securing means. Rods I 43 may be reciprocated by any suitable operating mechanism, such as that shown for the rods 33 in Fig. 1. Thus upon reciprocation of rods I43 grate bars I02 and I04 will also be reciprocated to feed fuel I and refuse toward the ash pocket disposed at the lower end of the stoker. This construction also functions to break up any clinkers forming at the top of the fuel bed.

Figs. 19 and 20 show a still further modification of the present invention. In this construction the overfeed section I60 of the stoker I6I consists of a series of alternately disposed fluid conducting tubes I62 and feeding elements I63. The fuel feeding elements in this construction comprise a series of endless chain units I54 which are trained about sprocket wheels I65 and I66 mounted in suitable brackets I61 and I68 respectively, extending upwardly from any suitable framework I69. The overfeed section I60 may comprise a number of independently operable units. For the purpose of illustration, however, two units indicated at I60 and I60 are shown in Fig. 20. Mounted on a shaft I10 upon which the sprocket wheels I65 for section I60 are supported, is a sprocket wheel I1I Sprocket wheel I1I is connected to a second sprocket wheel I12 secured to one end of a drive shaft I13 extending transversely of overfeed section I60 by a chain I14 Shaft I13 is mounted in suitable bearing brackets I15 and I16 secured to and extending rearwardly of the front wall I11 of the air supply chamber I18 disposed beneath the overfeed section I60. Secured to shaft I13 and disposed between bearing brackets I15 and I10 is a ratchet wheel I19 Loosely mounted on shaft I13 and disposed on either side of ratchet wheel I19 are a pair of operating levers I and I8I having pivotally connected intermediate the ends thereof at I82 an operating pawl 183 Pawl 33 is held in engagement with ratchet wheel I19 by a weight I84'--. The upper ends of levers I80 and I8I are pivotally connected to a coupling I85 mounted at the rearwardly disposed end of a rod I36 slidably supported in bearing I 81 and I88. Rod I86 may be reciprocated by any suitable power mechanism, such as that shown for the rods 33 in Fig. 1. Thus upon each rearward movement of rod I86 a rotary movement is imparted to ratchet wheel I19 shaft I13, sprocket wheel I12 sprocket wheel I 1P and sprocket wheels I65 and I 66 thereby causing a rearward travel of the upper section of chains I 64 Ratchet wheel I19 is held against movement in the reverse direction by a holding pawl I90 pivotally mounted on bearing bracket I15 as shown in Fig. 17. Thus upon the return movement of rod I86 pawl I33 simply ratchets over ratchet wheel us To increase the effectiveness of the overfeed section each chain 164 has provided thereon a series of vertically disposed feeding elements I64.

Section I60 is. similar in construction to section I60 and is also driven by a reciprocating rod 186 through ratchet wheel H9 secured to a shaft H3", and the chain and sprocket drive mechanism I'H I'M and I'll", as shown in Fig. 20. By dividing the overfeed section Hill into units, such as I60 and [60, the units are adapted for relative movements which may be desirable under certain conditions of operation. It also is possible by this. construction to vary the strokes of reciprocating rods 186 and ist to thereby vary the feeding capacity of the individual units and in this way maintain the desired fuel bed conditions. The strokes of the individual units may be varied by varying the number of individual washers shown at 201! on the operating mechanism in Fig. 1.

From the foregoing description it is seen that each of the various forms of overfeed sections herein shown effectively feeds the consumed or partially consumed fuel toward the ash pocket of the stoker, and also breaks up any clinkers forming at the top of the fuel bed.

By employing fluid cooled structures it is also apparent that the overfeed sections may be made relatively long, thus increasing the effective grate area without appreciably increasing the cost of the installation. The various overfeed sections just described are also of such a character that they may form the entire grate of the stoker if it is so desired.

It therefore is seen that the present invention affords a stoker design which is highly efiicient in operation, as well as economical in manufacture.

While the embodiments herein shown and described are admirably adapted to fulfill the objects primarily stated, it is to be understood that the invention is not to be limited thereto, since it may be embodied in other forms, all coming within the scope of claims which follow.

What is claimed is:

l. 'A stoker comprising an underfeed section and an overfeed section, said underfeed section consisting of a series of alternately disposed retorts and tuyere rows, dead plates disposed at the lower ends of said retorts, oneor more fluid cooled members mounted in cooling relation with each of said tuyere rows and dead plates, said members extending rearwardly of the underfeed section and forming a portion of said overfeed section, individual feeding elements disposed between the extended portions of said members and lying in substantial alignment with said tuyere rows and retorts, means for connecting said elements into groups transversely of said stoker, and independent operating means for each of said groups.

2. A stoker, comprising an underfeed section and an overfeed section, said underfeed section consisting of a series of alternately disposed retorts and tuyere rows, one or more fluid conducting members mounted in intimate relation with each of said tuyere rows, said members extending rearwardly of said underfeed section and forming a portion ofsaid overfeed section, a plurality of grate bars disposed between the extensions of said members in alignment with said tuyere rows and also forming a portion of said overfeed section, supporting means for the lower ends of said grate bars, means for elevating said supporting means to vary the effectiveness of said grate bars, cam means operatively connected to each of said grate bars for actuating the same, and means for operating said cam means.

3. A stoker, comprising an underfeed section and an overfeed section, said underfeed section consisting of alternately disposed retorts and tuyre rows, one or more fluid conducting members mounted in intimate relation with each of said tuyere rows, said members extending rearwardly and forming a portion of said overfeed section, a series of feeding elements disposed in overlapping relation between said members and also forming a portion of said overfeed section, the elements in line with said retorts being relatively wide, while the elements in line with said tuyre rows being relatively narrow, means connecting one of said relatively wide elements with one of said relatively narrow elements, and independent operating means for each pair of said interconnected elements.

4. An inclined grate stoker, comprising an underfeed section and an overfeed section, said underfeed section consisting of alternately disposed retorts and tuyre rows, tubes mounted in cooling relation with said tuyre rows, said tubes extending rearwardly and forming a portion of said overfeed section, a header for the lower ends of said tubes, movable feeding means disposed between said tubes and in line with said tuyre rows, additional feeding means mounted in spaced relation with said first mentioned feeding means and disposed in substantial alignment with said retorts, supporting means for said feeding means, independent of said tubes and means for actuating said feeding means to feed fuel and refuse toward therear 'of said stoker.

5. A stoker, comprising an underfeed section and an overfeed section, said underfeed section consisting of a series of alternately disposed retorts and tuyre rbws, deadv plates disposed at the lower ends of said retorts, one or more fluid cooled members mounted in cooling relation with each of said tuyre rows and dead plates,

said members extending rearwardly of the underfeed section and forming a portion of said overfeed section, individual feeding elements disposed between said members, certain of said feeding elements comprising a substantially rectangular body portion, a pair of laterally extending supporting flanges disposed at the lower edge of said body portion, a pair of laterally extending projections provided at the upper end of said body portion for supporting the upper end thereof, and means for actuating said feeding elements.

6. A stoker, comprising an underfeed section and an overfeed section, said underfeed section consisting of a series of alternately disposed retorts and tuyre rows, dead plates disposed at the lower ends of said retorts, one or more fluid cooled members mounted in cooling relation with each of said tuyere rows anddead plates, said members extending rearwardly of the underfeed section and forming a portion of said overfeed section, individual feeding elements disposed between said members, certain of said feeding elements comprising a body portion consisting of a pair of parallel plates disposed in spaced relation, a series of connecting members for said plates disposed in stepped relation along;

the upper edges thereof, supporting means pro:- vided at the lower edge of each of said plates,

laterally extending bearing means provided near the upper ends of each of said plates, and means for actuating said feeding elements.

7. A stoker, comprising an underfeed section and an overfeed section, said underfeed section consisting of a series of alternately disposed retorts and tuyre rows, dead plates disposed at the lower ends of said retorts, one or more fluid cooled members mounted in cooling relation with each of said tuyre rows and dead plates, said members extending rearwardly of the underfeed section and forming a portion of said overfeed section, individual feeding elements disposed between said members, means for connecting said feeding elements into groups, each group comprising an intermediate element having a body portion consisting of a pair of parallel plates disposed in spaced relation, a series of connecting members for said plates disposed in stepped relation along the upper edges thereof, supporting means provided at the lower edge of each of said plates, and laterally extending bearing means provided near the upper end of each of said plates; and one or more end elements disposed at either side of said intermediate element, each of said end elements comprising a substantially rectangular body portion, a pair of laterally extending supporting flanges disposed at the lower edge of said body portion, a pair of laterally extending projections provided at the upper end of said body portion for supporting the upper end thereof, and boss means provided near the lower edge of said body portion; and independent actuating means for each of said groups of feeding elements.

8. A stoker comprising an underfeed section and an overfeed section, said underfeed section consisting of a series of alternately disposed retorts and tuyere rows, one or more fluid conducting members mounted in intimate relation with each of said tuyere rows, said members extending rearwardly of said underfeed section and forming a portion of said overfeed section, grate bars disposed between the extensions of said members in alignment with said tuyere rows and also forming a portion of said overfeed section, supporting means for the upper and lower ends of said grate bars, means for adjusting the lower of said supporting means for said grate bars to vary the effectiveness thereof, and means for actuating said grate bars.

9. A stoker comprising an underfeed section and an overfeed section, said underfeed section consisting of a series of alternately disposed retorts and tuyre rows, dead plates disposed at the lower end of each of said retorts, one or more fluid conducting tubes mounted in intimate relation with each of said tuyere rows and dead plates, said tubes extending rearwardly and forming a portion of said overfeed section, individual feeding elements disposed between the extended portions of said tubes, supporting means for the upper and lower ends of said elements, means for actuating said elements, and means for adjusting the lower supports for said elements to vary the effectiveness thereof.

10. A stoker comprising an underfeed section and an overfeed section, said underfeed section consisting of a series of alternately disposed retorts and tuyre rows, dead plates provided at the lower ends of said retorts, one or more fluid conducting tubes mounted in cooling relation with said tuyre rows and dead plates, said tubes extending rearwardly and forming a portion of said overfeed section, individual grate bars disposed between said tubes and lying in juxtaposition therewith, supporting means for the upper and lower ends of saidgrate bars, the lower of said supporting means for said grate bars consisting of rocker arms having anti-friction rollers rotatably mounted thereon in engagement with the lower ends of said grate bars, a shaft to which said rocker arms are secured, gearing for actuating said shaft to adjust the position of said rollers, means for holding said shaft in adjusted position, and operating means for said grate bars.

JOSEPH S. BENNETT. 

